Intermediate superheater for high-pressure steam plants



v I s. LO-FELER H 1,800,306

INTERMEDIATE SUPERHEATER FOR HIGH PRESSURE STEAM PLANTS Filed April 18, 1927 Patented Apr. 14, 1931 UNITED STATES PATENT OFFICE STEPHAN LbFFLER, F CHARLOTTENBUBG, NEAR BEEIPIN, GERMANY; JENNY ELFRIEDE LFFLER SOLE HEIR OF SAID STEPHAN LOFFLER, DECEASED INTERMEDIATE SUPERHEATER FOR HIGH-PRESSURE STEAM PLANTS Application filed. April 18, 1927, Serial No. 184,730, and in Germany April 22, 1926.

The customary constructional forms of intermediate superheaters for high-pressure steam plants, in which low-pressure steam is superheated by condensing high-pressure live steam are characterized by the feature that the heating surface is formed by a plurality of coiled pipes housed in a vessel through which the steam to be superheated is flowing. There results from this arrangement a bad heat transmission and large dimensions ofsaid vessel.

In. eont'radistinction thereto the gist of the present invention consists therein that coiled double-pipes are employed. The heating-steam is made to flow through the inner coil or coils in downward direction, and the steam to be superheated is made to flow through the tubular space between the outer surface of the inner coil and the inner surface of the outer coil.

I am aware of the fact that coiled doublepipes are known and have been used as steam-generators, but this is not my object, in that I make use of them as intermediate superheaters that are not exposed to furnace or ,fire gases; these intermediate superheater-s excell the known ones by their high superheating, their small requirement of space, and their low weight.

The invention is illustrated diagrammatically and by way of example on the accompanying drawing, on which Figure 1 is a vertical axial section through an intermediate superheater designed according to this invention, and Figure 2 is a plan of the same. I

This intermediate superheater consists of a plurality of coiled double-pipes, each composed of an inner pipe A and an outer pipe B. The high-pressure steam, i. e. the heat ing-steam, flows through the inner pipes, and the steam to be heated through the outer pipes, that is to say, through the tubular passage existing between the two pipes. The windings of the outer pipes touch one another. Although I prefer coils that are circular in plan, as in Fig. 2, still, also coils of other shape, for instance of elliptical shape, may be made and used. plurality of coil is used. as in Figs. 1 and 2,

Where a they are made of different diameters, their dimensions being such that the coils may.

be put one into the other, as shown. But then their axial lengths are different by so much that the heating surface of all coils is equally large. Constructional forms of this kind are particularly useful, in that they require only very little place in com parison to the largeness of their heatexehanging surface, and the loss of heat by radiation is very small. It is practically zero when the outermost coil is provided with a lagging of a heat-insulating material; besides, it is suited to the purpose to fill the spaces between the individual coils with a similar material, for instance a slag or the like.

Owing to the fact that the intermediate superheater consists of coiled double-pipes, the transmission of the heat from the heating steam to the steam to be heated is very good, and it is possible without any difficulty to employ superheated live steam as heating steam. In this case, the two, kinds of steam must, however, be conducted in counter-current with respect to one another.

wards, as from the points a to the points I).

I wish it to be understood that I do not limit myself to enclose only one pipe A in a pipe B; it is possible to enclose two or three pipes A in one pipe B. If two or more pipes are connected up in parallel, it is proper to let them have equally large heat-exchanging surfaces.

I claim:

1. An intermediate superheater for highpressum steam plants in which low-pressure lOO steam is to be superheated by highressure steam, comprising a continuous coi ed double-pipe, the twopipes being so arranged as to have their common axis directed vertically, the inner pipe receiving the highpressure heating steam at its upper end which flows downwardly therein, and the outer pipes receiving the low-pressure steam at their lower ends which flows upwardly therein.

2. An intermediate superheater for highpressure steam plants in which low-premure steam is to be superheated by high-pressure steam, comprising a plurality'of continuous coiled double-pipes, the diameters of the several coils being different and the smaller coils being arranged in the larger ones, the inner pipes of the double-pipes being connected with a pipe or pipes supplying the I high-pressure heating steam, and the outer pipes of the double-pipes being connected with a pipe or pipes supplying the lowpressure steam, said coils being disposed in concentric spaced relation, the outer pipes of each coil having intimate contact throughout their length.

In testimony whereof I afiix my signature.

STEPHAN LGFFLER. 

